The present invention has for its object a device for positioning an operating member, of the type in which an operating member provided with displacement means is coordinated with an explorative member intended to explore the object on which the operating member should act, in order to determine the correct positioning of the operating member. The invention also has for its object a welding apparatus using one or more said positioning devices, wherein said operating member is a welding head. The invention further has for its more specific object a welding apparatus of the mentioned kind (a so-called xe2x80x9ccouplerxe2x80x9d) particularly intended to perform the inner weldings between the sections of a tubing, such as an oil pipeline or the like.
In the known positioning devices of the mentioned kind, the explorative member generally is of an optical type, and it is displaced, independently from the operative member, within the field determined by the object on which the operation is to be performed, in order to plot some features of this object, suitable for determining the positions from which the operating member should then act. The results of the exploration are transmitted to a computer which, pursuant to a suitable interpretation of these data, controls the displacement means of the operating member in such a manner that this latter is carried in the thus determined positions. The whole of the employed means and of the operations that they should perform involves noticeable costs and, in view of the fact that several passes and elaborations are needed for arriving to position the operating member, the precision that can be attained may result relatively reduced or uncertain.
A first object of this invention is therefore to propose a device of the mentioned kind for the positioning of an operating member, which should be more simple in structure and operation and, through easily programmable operations, should ensure a high precision in the positioning.
A particular object of the invention is to allow using an explorative member having a purely mechanical nature, and therefore being simple, inexpensive, sturdy and free from any uncertainty and from sensitivity to troubles of any kind.
Still another object of the invention is to propose such a positioning device which should be particularly suitable for positioning a welding head in a welding apparatus.
In more specific applications, the invention aims to provide a positioning device particularly suitable for the use in an apparatus intended to perform the inner weldings between the sections which compose a tubing, such as an oil pipeline or the like.
As a consequence, it is also an object of the invention to provide a welding apparatus employing, for the positioning of the welding head or heads, positioning devices according to the invention, and a more specific object is to provide a welding apparatus, a so-called coupler, specifically intended for performing in an entirely automatic way the inner weldings between the sections intended to compose a tubing, such as an oil pipeline or the like.
The positioning device according to the invention is mainly characterized in that said explorative member is a mechanical touching member, that it is solid with the operating member, and that it is displaced together with the operating member by computer controlled displacement means, which are common to both the touching and the operating members.
In more detail, both said operating member and said touching member are mounted on a common supporting member on which act said computer controlled displacement means, thus forming a touching and operating unit.
Therefore, said mechanical touching member may be displaced, under control of the computer, in such a manner as to contact in succession, along different directions, a region of the object on which the operating member should act, in order to exactly determine the position in the space of the object and, more particularly, of its region on which the action should be performed.
Said determination takes place as a consequence of the stop of the explorative member, which happens when the explorative member contacts the object along a certain displacement direction. Therefore, when the different stop positions in which the contact has taken place have been memorized, it is then sufficient that the computer controls the same displacement means in such a way as to attain positions which are displaced, with respect to the memorized positions, of the fixed distance existing between the touching member and the working point of the operating member, in order to position this latter in the more precise possible way and without any intervening uncertainty.
The solid connection between the explorative member and the operating member, as well as the use of displacement means which are common to both said members, simplifies the device structure and prevents any mistake possibly due to different behaviors of separate displacement means for the explorative member and the operating member.
The use as explorative member of a simple mechanical touching member simplifies at the most and renders inexpensive the device structure and ensures the greatest simplicity in the interpretation of the information given by the explorative member.
Advantageously, said computer is programmed in order to determine by means of the touching member, and to memorize, the position of a plurality of points on which the operating member should perform its operation, then determining by interpolation the entire work trajectory of the operating member.
The displacement means are preferably arranged for providing positioning displacements of the operating and touching members according to a first and a second directions, mutually orthogonal, and to provide for the working shift displacements according to a third direction, orthogonal with respect to the first and second ones.
Said operating member may advantageously be a welding head. The unit formed by a touching member and an operating member being a welding head is advantageously included, in the number of one or more, in a welding apparatus, and particularly in an apparatus, a so-called coupler, intended to perform the inner weldings between the sections of a piping, such as an oil pipeline or the like.
Preferably, said welding apparatus comprises a body having means for being immobilized inside a tube section, and a revolving portion shaped like a roundabout, which carries said touching and operating devices. The body may comprise expandable jaws arranged in crowns, intended for centering and immobilizing said body inside the tube section. Particularly, the body may comprise three crowns of expandable jaws, namely: a rear crown having a centering and anchoring task, a front crown for anchoring the body to an already installed tube section, and an external crown for anchoring an additional tube section intended to be welded to the already installed tube section. The front and external jaw crowns may also have the task of improving, when needed, the circular outline of the end portions of the tube sections to be welded.
Advantageously, said body is provided with idle supporting wheels and driven advancement wheels; it includes an autonomous control group comprising at least a computer and an electric battery, is provided with a control board and may be connected to external feed and control means through a composite cable.